Bitmap File Header

The bitmap file header contains information about the type, size, and layout of a device-independent bitmap (DIB) file. In both the Windows 3.0 and Presentation Manager 1.2 DIBs, it is defined as a BITMAPFILEHEADER data structure:

typedef struct tagBITMAPFILEHEADER {
        WORD        bfType;
        DWORD        bfSize;
        WORD        bfReserved1;
        WORD        bfReserved2;
        DWORD        bfOffBits;
} BITMAPFILEHEADER;

The following table describes the fields.

Field

Description

bfType	Specifies the file type. It must consist of the character sequence BM (WORD value 0x4D42).
bfSize	Specifies the file size in bytes.
bfReserved1	Reserved. Must be set to zero.
bfReserved2	Reserved. Must be set to zero.
bfOffBits	Specifies the byte offset from the BITMAPFILEHEADER structure to the actual bitmap data in the file.